How to count TTL pulses during 100ms ?

I need to count TTL pulses coming out of an instrument (particule
counter). The pulses appear randomly. I must count how many pulses
appeared in the last 100ms, and so on, every 100ms. I don't want
cumulative counts, but the number of events every 100ms.
I need a hardware clock, so that the counting pace cannot be disturbed
by Windows making some weird, unrequested, CPU-hungry task.
I fact, I need to do that for 2 identical instruments of the same kind,
and I have 2 cards with 2 counters each, total 4 counters. My idea
would be to use 1 counter as the clock for 2 other counters, but how to
trigger the counter value read ?
Thanks.

Hi,
In the example I gave you, you need to supply the TTL you want to count the pulse (connected on pin 37) and a TTL "clock" which is connected to PFI0. The TTL on PFI0 permits a hardware timing (100ms for example) to count the edges that occur on the TTL source.
If you do not need hardware timing, have a look at the example attached. You only have to connect the TTL source and the VI counts every 100ms (software timed) the edges that occur durind those 100 ms.
Hope it will help you,
Regards,
David D.
Application Engineer - NI France
01-02-2006 01:26 PM
Attachments:
Compatge des fronts toutes les 100 ms.vi ‏61 KB

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Counting TTL pulses within specified integration time

Dear all,
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...(Continued from prev post due to 500-char limit)
Now, here's a proposal for a method that should be able to work, though it'll require more data and more processing. One key area to watch out for under DAQmx is the property node for "Duplicate Count Prevention." The behavior changed between 7.1 and 7.3 (on E and/or M series, but not on TIO-based counters), then the defaults changed in 7.4, and something changed yet again in 7.5
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Counting TTL pulses at high speed

Hi all,
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One thing you can try is to set the counter input CI.DupCounterPrevention property, this setting will filter the input, it is possible that when the ctr 0 is slow then many of the values you are counting become zero as well and are filtered out, since they are nolonger points, the counter will not collect enough points before the time-out occurs and the counter input read times out. I am not sure if this is your issue but I found out the hard way that this occurs when I switched to daqMX where this feature was added. Let me know if it worked,
Paul
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CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Counting TTL pulses from A between TTL pulses from B

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I tried to get an example script using the DAQ assistant from LabWindows, selecting acquire signals -> counter input -> Edge count. The function that I got as a result was DAQmxCreateCICountEdgesChan, and I am afraid that it only takes the counter as an argument and not the second digital input that marks the intervals.

From your description it seems to me that the best option is to use two-edge separation measurement. I am not on a PC with CVI installed so I cannot point you to a specific example but this tutorial gives you a brief explanation and some guidance on examples to look at.
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Counting ttl pulses

Hello Everyone,
I am attempting to continuously record (i.e. time stamp) only positive (i.e. 'Logic High' event) TTL pulses from a PMT using a PCI-6602 board via a BNC-2121.
From reading the LabVIEW tutorials/examples it seems that I should be able to get very high precision (15 digits) from the "Get Date/Time In Seconds" VI. I need to be able to record times to the microsecond (at least). Yet when I look at the data it appears that for every digit less than a millisecond either a 9 or a 0 is recorded, which leads me to believe that I can't get better time resolution than a millisecond. Is there anything I can do to change this?
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I've attached my very basic VI below.
Cheers,
CJ
Message Edited by CJKS on 05-22-2006 11:53 AM
Attachments:
PMTcounter.vi ‏126 KB

Yes the simpliest way to do what you want is to count the time between rising edges using a counter (the 6602 has 8 80 Mhz 32-bit counters). Yo will not use digital io but time counting. The gate of your counter will be the TTL/Cmos pulse from your PMT and the source of the counter will be the 6602 master clock 80Mhz, so you can count clock ticks between photons, now you have a 12.5ns time resolution. You can use the system clock to get a time zero if you would like to use absolute time. The olny thing to keep in mind is that you will be limited to a maximum time between pulses of 2^32/80M or 53 seconds, you will get an overflow of your counter but usually this is not a problem with photon counting. You will be also limited to a maximum photon rate of about 20Mphoton events.sec this is also not a problem since the interesting photon events seem to happen between these time scales. if you want a longer time scale you cvan always casceds 2 counters to get 64bit resolution but this is probablu not necessary. Look at the buffered period measurment examples. You can easily scale this to 8 counters with 8 PMTs if desired with your curent hardware but this gets expensive. Goodluck.
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Count ttl pulse only over 2 V

Hi I have a problem while I was trying to count a ttl pulse by using the DAQ Assistant. The problem may be simple but I just cannot solve that since I am new to LabView.
There is a TTL pulse generated from our APD which is about 30 ns width, 5V. I want to use LabView to do the photon counting. However due to the noise, I would like to set a count limit of 2V, so the software only count the TTL pulse which is greater than 2V. But I cannot do that. There is no option to set the limit.
And our hardware is BNC-2110 and PCIe-6323.
Can someone help me with this? Thanks.
Solved!
Go to Solution.

Okay so perform a finite or continous read of your analog input. Then you can perform a threshold, where all values below 2 become 0. This can be done many ways but I'd suggest an auto indexing for loop and using a select function in the for loop. Then you can perform any normal edge detection you normally would to count pulses.
EDIT: Post some code if you can.
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How to count the pulses of an incremental encoder with PCI-6010?

Hi everyone,
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Hi YShZh,
The current Acquisition Mode setting is set to "1 Sample (On Demand)" and will therefore only ever give you the first count value. The fist count value is equal to the initial count value, which in your case is 0.
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Counting TTL pulses using USB 6008

Hi Folks,
I am trying to setup a performance monitoring VI for a manufacturing line.
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K2 Productivity-s.vi ‏60 KB

Search 'count'. Count Digital Events.vi is the most basic one of interest.
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Hello Photon Guy,
Thank you for contacting National Instruments.
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Attachments:
BNC-2110.JPG ‏105 KB

How to use counter output pulses to trigger analog input?

Hello all,
I hope the kind people using this forum can help me, a lowly beginner LV programmer! I have been attempting to create a VI that produces a user defined number of TTL pulses, separated by every n seconds. Each TTL would be outputted to a stimulator, which in turn generates its own TTL. Using the stimulator-generated TTL, I would like to trigger finite analog data acquisition (e.g. for every TTL, trigger the collection of a data sweep that contains 4000 samples (collected at 4000 Hz), with 1000 samples collected pre-trigger. I would like to also be able to see each data sweep as it is triggered on a chart. As I understand things (lots of online/book/forum reading), I should be using the counter output to generate my TTL pulses, and syncing each counter produced TTL with analog input, as well as using a reference trigger. Also, the AI part should be started first, so that I don' t miss any counter outputs. If it matters, I also need to use one of the AI channels to acquire the TTL, so I can see my stimulator-induced responses to the stimulator in time.
I am able to generate the TTL pulses from the counter output, but I am having a problem with the AI part. I am unsure how to sync the counter output with AI. Also, since I need to acquire pre-trigger samples, I would be needing to acquire samples continuously, but when I set 'continuous samples' on daqmx timing, the VI doesn't work (hence why's its set to 'finite samples').
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Attachments:
RC001 v_1.vi ‏49 KB

Hello,
Due to the fact that analog tasks themselves are not retriggerable, a
pulse train produced by a counter is always used as the sample clock
for the analog input task in order to recreate a retriggerable effect
for analog input. This can be done by creating a finite pulse train set
to retriggerable using the DAQmx Trigger Property Node, or the pulse
train could be continuous and just be gated by another signal. Neither
of these methods can be properly applied in hardware to create a
retriggerable reference trigger. You can however implement something
similar in software by just stopping and restarting your reference
triggered analog input task within a loop. There will be some delay
between when the task is stopped and restarted, as these events require
software intervention, but if there is enough time between when each
trigger signal is generated, there should not be any noticeable delay
or missed samples.
I have attached an example of this!
Mark B
===If this fixes your problem, mark as solution!===
Attachments:
RC001 v_1mod.vi ‏25 KB

How to measure the pulse duration of a TTL signal using AI?

Hi there.
I would like to know how to measure the pulse duration of a TTL signal using an Analog input.
These TTL signals comes from an ultrasonic sensor's output. The pulse width of the signal is
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However, i will like to know how can i do it using the AI instead.
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Attachments:
Acq&Graph Voltage-Int Clkv1.vi ‏190 KB

Hi Paul,
Today i tried using 2 different methods to read the pulse duration of my sensor signal.
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Method1:
Add a filter vi(lowpass/bandpass) and a timing and transition measurements vi.
Pulse duration is selected as the output. With some numeric conversion, a centimeter
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Method2:
Add a Mask and Limit Testing vi and a timing and transition measurements vi.
By adjusting my upper and lower limits, i manage to "filter" a single pulse out from the actual signal.
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Attachments:
Results_Waveforms.doc ‏141 KB

How to generate pulse during changing boolean value?

I need to generate short pulse during changing boolean value from 0 to 1. This pulse is needed to reset counter.
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Maybe sambody can give me some tips to do it in other way?
Thank you in advance.
Regards
Solved!
Go to Solution.

Rogal wrote:
I need to generate short pulse during changing boolean value from 0 to 1. This pulse is needed to reset counter.
I was trying with Event Structure with Value Change but I think that I did something wrong.
Maybe sambody can give me some tips to do it in other way?
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We assumed you wanted a pulse when a front panel button (boolean) was clicked.
I am still not sure just what it is you want.
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Omar

How to count TTL pulses during 100ms ?

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